Status of Biodiversity in the Baltic Sea

The brackish Baltic Sea hosts species of various origins and environmental tolerances. These immigrated to the sea 10,000 to 15,000 years ago or have been introduced to the area over the relatively recent history of the system. The Baltic Sea has only one known endemic species. While information on some abiotic parameters extends back as long as five centuries and first quantitative snapshot data on biota (on exploited fish populations) originate generally from the same time, international coordination of research began in the early twentieth century. Continuous, annual Baltic Sea-wide long-term datasets on several organism groups (plankton, benthos, fish) are generally available since the mid-1950s. Based on a variety of available data sources (published papers, reports, grey literature, unpublished data), the Baltic Sea, incl. Kattegat, hosts altogether at least 6,065 species, including at least 1,700 phytoplankton, 442 phytobenthos, at least 1,199 zooplankton, at least 569 meiozoobenthos, 1,476 macrozoobenthos, at least 380 vertebrate parasites, about 200 fish, 3 seal, and 83 bird species. In general, but not in all organism groups, high sub-regional total species richness is associated with elevated salinity. Although in comparison with fully marine areas the Baltic Sea supports fewer species, several facets of the system's diversity remain underexplored to this day, such as micro-organisms, foraminiferans, meiobenthos and parasites. In the future, climate change and its interactions with multiple anthropogenic forcings are likely to have major impacts on the Baltic biodiversity

Meiobenthic communities of the Szczecin Lagoon

Based on data collected at 7 stations 4 times a year in 1985 and 1986, composition and distribution of meiobenthic communities in the Polish part of the Szczecin Lagoon, a eutrophic and polluted water body connected with the Baltic Sea, is presented. The data show a tendency to reduced total meiobenthos densities and diversity from the lower to upper reaches of the lagoon. The meiobenthic communities studied were dominated by nematodes, ostracods ranking second in numerical importance. Harpacticoid copepods were most abundant at the outer stations which are influenced by Baltic inflows. Most of the 10 harpacticoid species recorded in the lagoon were found at the outer stations (lower reaches) as well. Similarity analysis allowed to separate three zones within the lagoon: (1) the outer zone, its stations showing most abundant and diverse meiobenthic communities; (2) the innermost zone (upper reaches) with the least abundant and qualitatively impoverished communities; and (3) the intermediate zone

Feeding and food composition of sprat from Bornholm Depth

1048 sprat stomachs were subjected to analysis and determination of: qualitative composition of food; average weight of food; percent (quantity) of empty stomachs; index of fulfilment acc. to Blegvad; frequency of plankton appearance in food according to Hertling and nourishment coefficient acc. to Fulton

Certain biological features of sprat Sprattus sprattus balticus (G. Schneider) from Bornholm Depth

The investigations of Baltic sprat have been carried out for many years, while the sprat of Bornholm Depth had never been subjected to any definite biologic analysis. Subjected to these investigations was the sprat obtained from industrial catches during 1969 and 1970. The length of body, rate of growth, age, participation of sexes, maturity of gonads and the period of spawning were investigated and determined. The stomachs of sprats were analysed for composition during the whole year

The use of fast convolution and correlation analysis to increase the resistance of digital location

The method of analog location with the use of devices with SAW that is now being used in our country is fast, however it is nof accurate enough and has insufficient resistance to bofh natural and artificial noise. In the paper is proposed to increase the resistance of the digital location system by means of using a location system manipulated with noise-like code, and additional signal compression, filtration based on fast convolution and correlation analysis to isolate noise-like codes. The system proposed here easily adjusts to the changes in the code of the signal generated by the radar, and it also works in real time